A quantitative evaluation of pigmented skin lesions using the L*a*b* colorcoordinates

The evaluation of pigmentary skin lesions by clinical doctors has been base d on subjective and qualitative judgements. Observations have mostly relied on visual inspection, making the effects of treatment difficult to evaluat e with any precision. For this reason there is a real need for an objective method to evaluate prognosis after treatment. Recent scientific measuremen ts such as reflectance spectrophotometry and reflectance colorimetry have p rovided accurate quantitative color information about skin lesions, but the se techniques are costly and difficult to apply in the clinical field. The purpose of this study was to develop a simple and cost-effective way of eva luating treatment results. We have developed a software program using the L *a*b* color coordinate system to quantify the effect of treatment and have successfully demonstrated its clinical usefulness. Our method compares the relative color difference between normal skin and skin lesions before and a fter treatment, instead of measuring the absolute color of skin lesions. Th e accuracy of our quantitative color analysis was confirmed by the simulate d images of hemangioma and ota nevus. Clinical efficacy was also confirmed through a blind test involving 3 clinicians who were asked to grade the tre atment effects of 13 cases of hemangioma and 7 cases of ota nevus. These su bjective clinical grades correlated well with the treatment results obtaine d using the proposed color analysis system (Correlation coefficient = 0.84) .